Suture 101

Ryan Fitzgerald, DPM familiarizes the viewer with the basic types of suture materials available and their general application in lower extremity surgery. This presentation includes a discussion of the various common absorbable and nonabsorbable sutures, how they are classified, and general suture techniques which are commonly utilized by foot and ankle surgeons.

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Ryan Fitzgerald
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Lecture Transcript

Suture 101~1 Present e-learning systems.~2 Hello, my name is Doctor Ryan Fitzgerald and I am a current third year resident at the Washington Hospital Center in Washington D.C. Today we will be discussing the various suture materials available, their properties, handling characteristics, and common usages. As well as discussing the most common suture techniques employing lower extremity surgeries.~3 Production of this Present lecture was made possible by a generous grant from Amerx Healthcare Corporation, makers of Amerigel, the effective low cost alternative.~4 The purpose of this lecture is to familiarize yourself with the various types of suture material and techniques implored in extremity surgery. In this lecture, we will discuss the various types of suture materials available; discuss the various types of needles and their applications; and identify commonly employed closure techniques, which you will utilize in lower extremity surgery.~5 When determining which suture material to utilize given application, it is important to understand the adherent suture characteristics, which are specific to the various materials employed. These include: appropriate suture size, knot security, initial and retained tensile strength, rate of absorption, ease of handling, and potential for inflammatory reaction.~6 Suture materials can be classified as non-absorbable or absorbable based upon their adherent breakdown characteristics in the body. Naturally occurring filaments are really reactive and therefore, not often utilized in lower extremity surgery. Braided sutures are made of several thin strands of suture material braided together. Braided suture is easier to tie than non-braided suture and also, offers the advantage of increased knot security. However, braided sutures offer the possibility of proliferation of microbes within the inner stitches of the braids where such microbes are protected against normal host response. Monofilament suture is recommended for most skin closures. This suture offers less resistance when passing through the tissue and resist harboring microorganisms. Despite these advantages, care must be taken when utilizing monofilament sutures to avoid knot slippage.~7 As you can see from the table provided, there are four major types of non-absorbable suture. Nylon which can be either braided or monofilament and is known by the trade name Ethilon or Nurolon; braided polyester which is braided and known as Ethibond; polypropylene which is a monofilament, which is known by the trade name Prolene and stainless steel which can be either monofilament, twisted, or braided.~8 Nylon which is also known by the trade name Ethilon is a braided or monofilament suture. If this suture demonstrates low tissue reactivity, fair to good knot security, and is often utilized in ligament repair and skin closure.~9 Braided polyester also known as Ethibon is of course braided. This suture demonstrates low tissue reactivity with the coating intact; is known for having poor knot security, but is often utilized for skin, ligament, and tendon repair.~10 Polypropylene or Prolene suture is a monofilament suture that demonstrates minimal tissue reactivity. This suture demonstrates good knot security with easy handling despite having memory. This suture is most commonly utilized in skin closure.~11 Stainless steel suture which is available in monofilament, braided, or twisted. It's nonreactive, demonstrates excellent knot security, but has poor handling.~12 There are five major types of absorbable suture: glycolic acid, which is a monofilament otherwise known as Maxon; polygactin 910, which is braided otherwise known as Vicryl; polyglycolic acid which is braided, known by the brand name Dexon; polydioxanone which is a monofilament and is known as PDS II; and polyglecaprone 25 which is a monofilament otherwise known as Monocryl.~13 Glycolic acid also known as Maxon is a synthetic monofilament. This suture demonstrates minimal tissue reactivity, good knot security, and has been shown to retain 55% of its tensile strength at two weeks. This suture is commonly utilized in subcutaneous high tension closure and vessel ligation.~14 Polyglactin 910 also known as Vicryl is a braided suture which is commonly coated to facilitate tissue passage. This suture loses approximately 40% of its tensile strength within 14 days of placement. There is an additional loss of 70-80% of tensile strength at 21 days. This suture is commonly utilized in subcutaneous high tension closure and vessel ligation.~15 Polyglycolic acid also known as Dexon is a braided synthetic suture which loses 33% of its tensile strength at 30 days. Complete absorption is noted to occur between 90-120 days. This suture is commonly utilized for subcutaneous closure and vessel ligation.~16 Polydioxanone or PDS II is a monofilament suture. This suture provides longer tensile strength to the healing wound. Additionally, there is decreased tendency to harbor bacterial contaminants as compared to braided suture and therefore, this suture can be safely used in infected wounds. This suture demonstrates good knot security and 50-60% of tensile strength at four weeks with total absorption at around 180 days. This suture is commonly utilized in high tension, subcutaneous closure.~17 Polyglecaprone 25 also known as Monocryl is a synthetic monofilament. This suture demonstrates high initial strength with reduction to 50% at seven days. This suture is minimally reactive and demonstrates good knot security. In addition to excellent handling characteristics, this suture is most commonly utilized for subcuticular and skin closure.~18 The table provided demonstrates the continum the tissue reactivity of non-absorbable suture. Increased tissue reactivity is associated with increases in local inflammation which can hinder wound healing and should be avoided whenever possible. Polypropylene or Prolene is one of the least reactive sutures available. In contrast, naturally occurring fibers demonstrate the greatest tissue reactivity and are therefore, not commonly utilized in lower extremity surgery.~19 when considering suture classification it is important to understand suture size. Suture size which is determined by the USP or United States Pharmacopia is based on tensile strength. Sutures are sized according to the diameter of suture material necessary to withstand a certain tensile strength. For example, two 4-0 sutures of different materials will have different diameters. The baseline is zero. Whole numbers such as one, two, and three indicate larger than baseline. Sutures smaller than baseline is indicated with the addition of a zero following the number. For example, 3-0 is smaller than2-0. The most commonly utilized suture in the lower extremity surgery includes 2-0 and 3-0 for sticker skin areas and for those areas under great tension. 4-0 and 5-0 sutures are utilized in areas of the thinner tissue and when a more cosmetic closure is preferable.~20 The basic terminology of needle design for subcutaneous usage define three sections of the needle into the point, the body, and swage.~21 Suture needles demonstrate various types of points and degrees of curvature along the body. Needle points are either: blunt, tapered, triangular, or are diamond. In lower extremity surgery common needle types include: reversed cutting, conventional cutting, and taper. Taper needles are ideal for passage through friable tissue because of the low potential for cutting or tearing. Cutting needles are essentially triangular needles with the apex or triangle at the internal or external arc of the needle depending on whether they are conventional or reverse cutting. These needle types are useful in penetration of dense, thick tissue. The body of the needle demonstrates a certain core length and degree of curvature or is straight in the case of a Keith needle. The degree of curvature or core length is an important consideration when selecting a needle and is measured in the terms of degrees of an arc around a circle. From 1/4 circle to 2/3 circle to 1/2 circle.~22 To have the greatest success in suturing, it is important to load the needle driver correctly. First, grasp the body of the needle with the needle driver. You don't want to grasp the swage which is a common error. Next, position the needle driver in hand to allow for maximum pronation and supnation of the wrist. Finally, stabilize the needle driver with your index finger. This will allow for increased stability through rotation along the needle arc.~23 When considering suturing techniques, it is important to understand the common suturing errors: which include too many throws, excessive knot tying will increase foreign body size; holding the swage of the needle which will cause the needle and the suture material to separate as well as potential needle breakage; and directly holding monofilament suture with the instruments which can cause damage to the suture or breakage.~24 There many different types of suture techniques available to the surgeon depending upon the location of suture placement and the desire to factor the suture. For the purpose of this lecture, six techniques most commonly utilized in lower extremity surgery will be discussed which include: simple interrupted, vertical mattress, horizontal mattress, continuous locking, subcuticular, and retention. Interrupted sutures are individually placed and tied and are the technique of choice when cleanliness of the wound is an issue. Continuous sutures are placed again and again without tying the individual suture. Thus, these sutures are easy to perform and are preferred if the wound is clean. Both interrupted and continuous suture can be utilized on the surface or deep within the tissues depending on the type of suture material being utilized. The purpose of buried suture is to re-create normal, functional tissue layers and to eliminate dead space.~25 When considering suture technique it is appropriate to consider knot tying. There are essentially two techniques for knot tying available to the surgeon; the in instrument tie, in which the surgeon utilizes the needle driver in tying the knot's or the hand tie where the surgeon utilizes his hands to tie the knots. In this way, the surgeon can employ either the one or two handed technique to create a knot in the suture.~26 The simple interrupted is a ubiquitous technique which is commonly utilized in deep closure as well as skin closure. In this technique the surgeon ties a knot after each throw of the suture. The needle enters the tissues at a 90° angle and in this way allows for the full arc of the needle as the hand is supinated.~27 In this video, the simple interrupted technique. As you can see in this technique, the needle is passed from one skin edge to the next and the knot is tied. Often this technique is utilized in rear approximation of the tissues and superficial skin closure.~28 The vertical mattress suture technique allows for closure of deep and superficial layers of the incision and is strong under tension. To utilize this technique the throws are far-far, near-near.~29 The resident in this video is utilizing the vertical mattress suture technique. This technique is often utilized in areas of high tension to provide full thickness of this closure. As you can see, to perform this technique the throws are far-far, near-near which is to say the first incision the second throws are wider from the skin edges and the third and fourth throws are closer to the skin edges. Upon completion of the final throw, the knot will be tied off to one side.~30 The horizontal mattress suture technique provides for excellent skin e-version and allows for full thickness closure. This technique is useful in areas of high tension and is essentially two simple “un-interrupted” sutures.~31 In this video, the surgeon is closing using the horizontal mattress technique. This technique provides for excellent skin e-version and is useful in areas of high tension. The horizontal mattress suture technique allows for full thickness closure and is essentially two simple “un-interrupted” sutures thrown on after the other. It is important when tying the horizontal mattress suture, that you not over tighten the knot. For this can cause skin edge necrosis.~32 The continuous suture technique may be locking, horizontal, or subcuticular and may utilize absorbable or non-absorbable suture. This technique is most commonly utilized in skin closure; especially in those situations when a cosmetic result is preferable. If the surgeon is to use a non-absorbable suture, it is important that bridges be oriented along the course of the incision to allow for removal of the suture upon wound healing.~33 The subcuticular suture technique us a variation on the previous discussed continuous technique. In this way, it’s an intra-dermal continuous stitch which may be combined with one or more cosmetic closure and is commonly utilized in elective surgery.~34 In this video, you can visualize the running subcuticular suture technique. This technique is an intra-dermal continuous stitch. When using non-absorbable suture, this technique may be combined with one or more external bridges to allow for easier removal. This technique is commonly utilized in elective surgery to provide a more cosmetic closure.~35 The retention suture technique which is also known as the trauma stitch is useful for closure in areas of high tension and tissue re-approximation. To utilize this technique the throws are far-near, near-far.~36 The retention suture or trauma stitch is essentially a variation on the vertical mattress suture technique. This technique is commonly utilized for closure in areas of high tension. Unlike the vertical mattress, the throws for this technique are far-near, near-far which is to say the first and fourth throws are farthest from the incision edge, while the second and third throws remain near to the edge. This is visualized in the video.~37 In this video, the two-handed tie will be demonstrated. When learning hand ties, it is often quite useful to initially practice utilizing a larger diameter string, such as shoe string before moving on to actual suture. Both methods will be demonstrated there. Often this suture technique is utilized to ligate bleeding vessels or to ensure the appropriate level of tension is applied by the suture knot. The two handed tie is so named because during the process, both hands move along the string to create the knots as is demonstrated in the video. To perform a two hand tie, first a figure four is created. The running end from the left hand it then passed through the loop created as you can see demonstrated by the photos here and the running end is passed back into the left hand which holds tension while the right hand releases the loop. At this point, the loop is snugged and against the vessel or soft tissue which is being tied. Your reverse loop is then made with the running ends and the tail from the right hand is passed through the loop, as is visualized here. The loop is the in snugged down and the knot is complete.~38 In this video, the one handed tie and is so named because throughout the technique you only move one hand. The suture in the second hand, in this video the right hand, remains stable which allows the surgeon to hand tie the suture that is not specifically designed for hand ties; one for example that includes a needle on the end. In the single handed tie, the end of the suture with the needle can be held stationary, which the knot is performed. As you can see visualized in the video, the left hand manipulates the running end of the suture while the right hand remains stable. In this way, the technique allows the surgeon to perform hand ties on suture that would normally require an instrumentation for knot tying. As was presented in the two hand tie video, a detailed description will follow. The same [inaudible] demonstrates the starting position for the single handed tie. Notice the needle driver clipped in the stable right end of the suture. The suture in the right hand is held stationary while the running end in the left hand will move. In this image, the suture from the right hand is looped under the finger of the left hand. The suture from the left will then be passed under the right, as is demonstrated here. In this image, you can see the running end from the left hand passed through the loop. The loop is in snugged down, as is demonstrated here. At this point, a second loop is created. To do so, the left hand is sucanated about the suture in the left hand; thus creating a loop, as visualized here. The stable end of the suture from the right hand is then laid across the left hand. The running end from the left hand is then placed through the loop created, as can be visualized in this picture. The loop is in snugged down tight and the knot is complete. This series is repeated to provide appropriate soft tissue ligation.~39 There are several special suture techniques which you may have the opportunity to utilize in your practice. These include the apical stitch as in figure “A” and the purse-string stitch as in figure “B.” The apical stitches are often referred to as a three point corner stitch and is useful in closing vettlewide plasties and z-plastie flaps. Purse-string sutures in the lower extremity are commonly utilized to enter post capsule within the first metatarsal phalange following Keller Bunionectomy.~40 In addition to skin closure techniques, it is vital that the surgeon be appropriately versed in tendon repair sutures. These include the multi-strand crackcal stitch as in figure “A,” the modified Kesler stitch as in figure “B,” and the modified Badel stitch as in figure “C.” All of these can be utilized to re-approximate tendon edges in primary tendon repair following rupture or release.~41 In conclusion, successful wound closure depends upon appropriate suture selection including material whether it be absorbable or non-absorbable, size, and needle type. Additionally, it is important for the surgeon to select the appropriate suture technique and finally, it is important that all wounds be closed with minimal tension to remote wound healing.~42 Production of this Present lecture was made possible by a generous grant from Amerx Healthcare Corporation, makers of Amerigel, the effective low cost alternative.~43 I appreciate your attention through this brief overview of suture classification and review of commonly utilized suture techniques. It is my hope that you would have gleaned something from this lecture that will aid you in your pursuits as a foot and ankle surgeon.